In The News

Scientists Discover Deep-Sea Bacteria Has a Metabolism Unlike Anything We’ve Seen Before

CARLY CASSELLA

3 APRIL 2020

A curious kind of bacteria found on the floor of the deep ocean might have a metabolism unlike anything we’ve seen before.

Known as Acetobacterium woodii, scientists in Germany claim that this species, which also lives in the intestines of termites, can both create and use hydrogen and carbon dioxide to produce energy all on its own, even without the need for oxygen.

The ability to survive on organic and inorganic substances alike without oxygen makes this bacterium quite unique among microorganisms, and while scientists have long suspected something like this existed, it’s never been clearly described among acetogenic bacteria, which produce methane free from oxygen.

“There have already been speculations that many ancient life forms possess the kind of metabolism that we have described in A. woodii,” microbiologist Volker Müller from Goethe University Frankfurt explains.

“This is assumed, for example, for the Asgard archaea that were just discovered a few years ago on the seabed off of California. Our investigations provide the first evidence that these paths of metabolism actually exist.”

Hydrothermal vents were only discovered in the late ’70s, and since then we’ve come to realise these strange habitats are home to complex and dynamic forms of life, including mats of bacteria several centimetres thick, which feed on inorganic compounds like hydrogen and sulphide, as they rush up through the subsurface.

The thing is, excess hydrogen inhibits the fermentation process, and even the weakest hydrothermal vents easily exceed the levels needed to harbour fermentative bacteria. So how is it that such microbes exist down here?

Apparently, the answer lies in sticking together. If one bacteria that produces hydrogen teams up with another microorganism that oxidises hydrogen, like methane-producing archaea, then the latter can maintain good environmental conditions for the former to live and reproduce.

(Adam and Perner, Frontiers in Microbiology, 2018)

It’s a helpful little friendship – or syntrophic relationship – deep under the sea, but while this is probably the dominant kind of fermentation that occurs in these environments, it may not be the only one.

The new analysis essentially claims to have found a microorganism capable of playing both roles in just one bacterial cell.

Oldest Photosynthetic Algae found in China

Article from NATURE

MICHELLE STARR

25 FEB 2020

Strange, vein-like shadows imprinted in ancient rocks are some of the most important clues yet in piecing together the timeline of photosynthesis. At 1 billion years old, the tiny fossils are the oldest example of green algae we’ve ever discovered.

Even from all those aeons ago, the fossils show evidence of characteristics in common with modern algae. They represent multicellular organisms with branching structures and even root systems.

Palaeontologists have named the newly discovered, ancient algae Proterocladus antiquus, and it beats the previous record-holder – the fragmentary Proterocladus, 800 million years old (it’s possible they’re both the same species).

This discovery suggests seaweed were already thriving in the ocean, long before plants migrated to dry land.

“Our study shows that green seaweeds evolved no later than 1 billion years ago, pushing back the record of green seaweeds by about 200 million years.”

(Tang et al., Nature Ecology & Evolution, 2020)

The fossils themselves are tiny, just a few millimetres long – flea-sized smears on sedimentary rock found in the Nanfen Formation in Liaoning Province, North China. But when studied under a microscope, their delicate, branching forms are crystal clear.

Older algae fossils have been found – a red alga called Bangiomorpha pubescens, which was dated to around 1.047 billion years ago. It’s also an important find for our understanding of photosynthesis, but P. antiquus is different because it’s green.

It’s thought that green plants – Viridiplantae – emerged sometime between 2.5 billion and 635 million years ago. Because ancient plant fossils are rare, narrowing that timeline down has been extremely difficult. Scientists also don’t know when they evolved from single-celled to multicellular organisms, or even where they started out.

Some believe that, just like multicellular animals, Viridiplantae started off in the ocean as seaweeds before moving onto dry land and evolving into all the different plants we have today, from the mightiest redwood to the smallest moss.

Others, however, believe that freshwater rivers and lakes gave birth to plants; from there, they moved into the ocean, before finally ending up on land.

P. antiquus supports an oceanic origin – because it’s extremely similar to seaweeds that are around today.https://www.sciencealert.com/these-fossils-are-seaweed-that-lived-a-billion-years-ago?